I overhauled my '24 Speedster engine last year and drove it to Spokane in September. With less than a thousand miles on the car I suddenly had to adjust the low-speed band twice — this, plus lots of Kevlar fuzz in the filter lead me to suspect a cracked low speed drum, which is exactly what we found at the roadside 600 miles from home. I backed the low speed band right off and we drove home in high gear.
This week I took the engine out to replace the low speed drum and found two cracks in that drum, a small crack and much lug wear in the brake drum, two broken large discs and one cracked small disc.
I'm looking for insight into why all this happened in less than 2,000 miles in hopes of not repeating the exercise again next year. I am aware of the dangers of adjusting new Kevlar too tight and riding the pedals and don't believe that was the case here (can't be sure of course). I have purchased my first set of wood bands and am planning to go this route with the overhaul as well as re-using original Ford discs as I have extra on hand.
I won't go into the "Kevlar Death" debate, but I must pose the question : Just what condition were the brake drum lugs prior to your "overhaul" ? If that was the actual wear after only 1000 miles, there was something clearly out of adjustment or ??????
The crack from the threaded hole is sometimes the result of hydraulicing. Oil in the hole when tightened.
Steve, I note the use of "quotation marks" around my use of the term "overhaul". Fair question. I like to think I'd have noticed this excessive wear at that time but I honestly can't recall. I took many photos during the build but not, unfortunately, of the "brake drum".
I agree, if it happened over 2,000 miles there must be something wrong, but what?
Chris,
Based on your photo's and my experience with T transmissions, I would have to agree the pitting and scoring on those drums didn't happen in 2K miles. The low drum also shows signs of heavy rust pitting even in the worn grove.
The brake drum shows a crack at a bolt hole suggesting over tightening. The clutch plate was slipping possibly from the excessive lug wear, or a poorly adjusted clutch.
If I were to speculate, I would say the transmission was pretty well gone and ready to die before your rebuild!
If you know your transmission was in good shape when the rebuild was done... you might ask the re-builder where your transmission went!
JMHO
That is pretty much the worst brake drum I have ever seen. I can't believe that happened in 1000 miles. Maybe 25000 in a model T.....
Sorry, 2000 miles still the same....
The wear on the brake drum lugs is indicative of perhaps 150,000 miles worth of wear. You got your money's worth out of that one, or someone else did.
Sorry, 2000 miles still the same....
Thanks, all for your comments. A bit more background... This transmission had been in the car for 20 years. Back then it was my first T and I got the transmission as a used assembly, looked it over and ran it as is. A few years ago I noticed a crack in the low drum then only drove the car occasionally until doing a full rebuild last year.
Anyway, I'm not suggesting the pitting and scoring only happened recently, and the used low drum I put in last year, now cracked, was pitted but polished, re-bushed and visually checked for cracks at the time.
Hydraulicing or over-tightening a driven plate bolt and cracking the brake drum makes sense. Thanks for that, and the replacement brake drum I have has much better lugs.
What about the clutch discs? These look pretty burnt, and I have more that are not so discoloured — how do you suggest I inspect and chose discs for re-use?
I agree--That's not 2000 mile wear on the lugs. Even if you were on and off the throttle like a bucking bronco, it wouldn't wear that much. That's what caused the clutch disks to overheat and crack. I can't see how you got a good free neutral with wear like that. Somebody missed something.
KK "That's what caused the clutch disks to overheat and crack..."
How so — because they could get hung up in the notches and not float back & forth easily when the clutch is depressed?
FYI "somebody" is me.
Yes, the disks must be able to "float" across the lugs.
As far as selecting good disks, the bluing alone won't hurt as long as they're smooth. If there's any scoring or metallic build-up, those are trash. It's indicative of excessive heat and galling. And, of course, the cracked ones go to the dumpster too.
Ken, lots of folks still shy away from discussing the Kevlar fraction of this equation because it is essentially a debate over religion.
Having used Kevlar unsuccessfully I am a devoted disciple of the no-Kevlar denomination.
The cracks in the drums (maybe excepting those over the bolt holes), the blue clutch plates and broken clutch plates are (IMHO) due to extreme high heat.
Heat in a transmission gets there from two sources: friction (bands, bearings, clutch) and conduction from the oil. At the temperatures your tranny attained if it was due to 850 degree or higher oil you would have smelled it and seen the smoke.
So I think that you need to consider the sources of friction... and you don't get drum surface fractures like that from bearings and have the bearings survive. The blue clutch plates can be from the clutch plates jamming on the rough lugs, but there isn't enough clutch plate to drum contact to pass adequate heat to break a drum.
There is one other source of friction caused heat... can you figure that one out?
Respectfully submitted, TH
I'm not shy about discussing Kevlar. I just didn't mention it in this thread.
Chris, when I pick out discs to use I throw away discs that are cracked, or badly blued or pitted. Then lay the others on a flat surface like a pane of glass to check the discs for being flat. Use only discs that are completely flat as warped discs will cause creeping and hard starting.
Stephen
I'm not shy either when it come to Kevlar. I prefer Kevlar in my '16 touring. The T100 team chose Kevlar for the "new T's".
The debate over wood, Kevlar or cotton band material is weak since no real data have ever been presented to support one material over the other that I'm aware of.
Yes, a great deal of anecdotal information has been logged here but that is not engineering data backed up by real measurements. JMHO
Thank to all, especially Ken, Terry, John and Stephen. I'm confident of a much better result this time around. This forum is such a great place.
Chris, Terry sidestepped blaming Kevlar bands for cracking your low speed drum. I would not use a drum as pitted as that one and expect any band material to last. No-one has suggested that a 90 year old lump of cast iron just quit! Those types of failures have been happening since Ts were put on the road. I have found two trans missions with bronzed up cracks like that, still in use, and with no idea how long ago the repair had been made. I put such failures down to old age.
It's a bit like the medical profession these days. Nobody dies of old age anymore. They die at 92 of cancer, or at 87 of heart failure.
I broke an axle on a 4500 mile trip to Western Australia. An 80 year old bit just quit. On the same run the end fell off a magnet clamp screw and let the clamp loose in the trans. I don't think it was the friction from the kevlar bands heating the oil too much and annealing the brass screw so the head fell off. Perhaps it was! Or did another 80 year old bit just quit!
Allan from down under.
I think the idea that wear is causing the drum failures is the right answer. You can make a drum fail a lot quicker by turning it down in the lathe to remove a lot of strength. I think a lot of drum failures come from that practice. Shiny and no rivet grooves is not stronger.
At the risk of offending the Kevlar devotees, I must respectfully say that I hold the opinion that, at least some of the blame lies with the use of Kevlar bands. When you get your transmission repaired, give Guinn's wood band linings a try. I doubt that the same thing will happen with this superior product.
It has long been surmised that a woven, harder than steel, material that is used in military helmets, ballistic armor and bulletproof vests, is simply too hard, non-absorbent (for retaining oil) and technologically advanced to use as a Model T band lining. That it is essentially like using steel on steel, which, when combined with friction and a lack of proper lubrication results in an excessive amount of heat, but as John Semprez says, there has not been enough studies to substantiate this theory. Only the experience of those like Chris who have suffered such a disappointing and mysteriously sudden failure in a relatively short period of time. As time goes by, the case against Kevlar is building. Jim Patrick
No disagreement with that Jim. Kevlar can be used to machine steel. In the end, anything that generates friction sufficient to move the car or stop the car is capable of removing material from the drums. Kevlar, being stronger than wood or cloth, certainly will generate more friction and thus more heat, and more rapid wear.
The key to longevity is driving technique. You can destroy a transmission with any kind of band material if you use the maximum braking ability frequently, or slip the bands frequently during starts in either low or reverse.
Here we go again. If you do not want to use Kevlar fine.
1. Far more failures are due to the practice of turning a drum down to get rid of the rivet marks. Rivet marks do not hurt a drum or weaken a drum. Put your drums in a lathe and use some sandpaper to polish them and then let it be.
2, Another NO NO is the practice of alternating low pedal and reverse when going down long hills. Can you imagine what jerking that does to drums. And then they blame it on the material that they are using. You should have enough compression in your motor to hold you back so you don't even have to use the brake let along reverse. If the hill is so steep shift down.
Jim, since the case is building against kevlar, can you point out the reasons so many use it for many thousands of miles without the disappointing and sudden failure in a relatively short period of time also? I would think that the T100 cars would get the most wear and tear of any of our cars. I really don't care what lining I use or anyone else for that matter, I feel the basic problem might lie in the fact that the linings are misadjusted as people get them adjusted too tight trying for a pedal like their modern car or sometimes people slip the bands and may not even realize it. And the debate continues....
Here we go again? We do a disservice to those seeking answers, whenever we avoid a subject that might offend or anger some. We must remember that while many of us have encountered the same argument dozens of times, there are some who are new here and have never heard the argument so it is new to them.
All we can do is provide our opinions, based upon our experiences, no matter how controversial, or provocative and let that person arrive at his own conclusions though doing his own research or by choosing what he feels is the most appropriate solution to his problem. Jim Patrick
Doug. Kevlar was introduced as a durable lining to replace the old style woven cotton Scandanavian linings that wear out prematurely, or too fast. Unfortunately, by introducing a lining made of one of the most durable materials on the planet, they defeated the whole purpose of what the transmission lining is supposed to do which is to wear out before doing damage to the drums.
Before the problems with Kevlar began to mount, people changed over to Kevlar for a durable band that lasts much, much longer than the ordinary lining and does not need to be changed out as much, but, more and more we began seeing reports of cracked drums on T's using Kevlar. I'm not making this up. These are conclusions arrived at by actual former users of Kevlar and reported on the forum and as more and more evidence trickles in, I believe you will see people start to change over to wood because, like me, they just don't want to take the chance that what happened to Chris will happen to them.
I had actually purchased a set of kevlar linings in 2010 to use on my car, but I decided against using them in favor of wood bands thanks to the advice of many respected forum members who did not avoid this controversial subject, but told me their true opinions and I thank them for that.
I agree with Dave and John. There is not enough data in to prove any of this and everyone is free to use whatever they like. I happen to like wood. If you like Kevlar, that is great for you, but if there is speculation that there are questions surrounding a particular product, we do no one any favors by concealing the problems by sweeping them under the rug in an effort to avoid upsetting those that may disagree or who don't want to hear it. Jim Patrick
Do modern cars have kevlar clutch linings?
Have any of you worn out a kevlar band lining? There has to be a sacrificial material, and I'd rather that be the part that's easiest to replace.
No tranny has suffered more indignity and wear than the one I pulled from the Fronty recently, after it jammed and tore the flange off the crankshaft, yet the drums were not hurt, at least partly due to wood band liners.
The inspector here is the guy who rebuilt this tranny back in '98, about 50K miles ago. One triple gear bushing was seized on the pin, and had scored it badly. I'm installing McEachern needle bearings on this go.
rdr
Funny thing, Jim, us crossposting with the same thoughts. I bought a set of kevlar linings back in '97, but before I got around to installing them, John Hale convinced me to buy the wood linings he was making. Glad I did it. He later sold the business to Jim Guinn.
Kevlar shredding means a full engine teardown to get all the abrasive fuzz out. Fun job..
rdr
I think there are two VERY IMPORTANT things: 1-the bands has to be total round after putting the linings on. 2-there should be no forward movement between the pedal and the support. Only side-forward movement.
Toon
I think a gap was built into the clutch cam so you get a little forward movement before camming action. Dunno why.
We have used Kevlar in our engines, since it came out. No broken drums, no more lint then any other fabric band, and I have yet to replace any of them, or have heard they needed it.
If you don't treat the ends with red insulation paint, they will ravel, as what they come with, that little ribbon of plastic on the ends, will NOT stop them from raveling. If you over tighten, they will burn black. They don't need to be as tight as other bands, as they are to tough to wear the 1/2, or 1 turn to tight off with out damage.
Old and worn transmission drums have to be treated as stated. "Old and worn". If you have a heavy foot and tend to use your foot aggressivly something is going to happen sooner and not later.
Herm, What is the reason for cutting the bands in half? Better cooling?
They let the band flex in the middle, and conforming better, and you will get more even wear, and it is also another place for oil to get in.
Kevlar users say they use Kevlar so they don't have to replace/adjust the bands so often. It is my opinion that the need for frequent adjustment or replacement is a result of poor driving habits. If those same driving habits are practiced with Kevlar, I could see a cracked drum in someone's future. If you do not have poor driving habits, then any lining will last you a long time. I run wood in my TT, and have for about 5 years. Other than initial wear in, I don't think I have adjusted them but once. It gets driven most every weekend.
Many of the pictures on the Forums show rebuilt transmissions, and with all the crude still left on the drums, I don't see how they would find any cracks, if they did have them.
I have never see a drum crack in rebuilt service, but to find good used drums, to rebuild, you will have a way bigger pile of cracked drums.
We adjust once, or twice, and that's it. Never any problems.
If you use junk, you can't expect much, but don't blame the wrong parts. If Kevlar bands cause cracked drums, I should have have at least one engine go bad.
How many people drive a modern manual transmission car and go through clutches often and others not so much. I agree alot of it depends on how it's driven.
When I lined the '27 Tudor bands I used Kevlar from Rocky Mountain and installed them the "Kohnke Way" as it makes sense to me.
I've been very conservative with tightness and have adjusted the low band several times but not the reverse or brake bands.
Doug is right on the MONEY.......
When I'm starting I sort of "double clutch" the low band. I bump it a little to get the car rolling and then clamp 'er down instead of slipping the band to get moving.
I think I'm done adjusting for a while AND the screen is staying clean now too since it got all the crud screened out from the old bands.
Darn, I'll have to get rid of my wood bands, now that they've been shown to cause the transmission to jam and rip the flange off the crank.
Funny, James. Actually, the wood band liners didn't look that bad. I'll probably replace the low band while I'm in there, just for PM, Preventive Maintenance.
rdr
Quote: "I have found two trans missions with bronzed up cracks like that, still in use, and with no idea how long ago the repair had been made."
I've often wondered why the drums couldn't be bronzed (brazed?) up and continued to be used, now I don't see any reason that they can't be.
I don't know whether the drums could be brazed and then polished smooth, but the crack across the low drum will shred the lining, whatever kind of lining you use if the drum is not smooth.
Norm
I've seen low and reverse drums cracked, but I don't think I've heard about a brake drum cracked yet? They've got more material and may survive excessive heat better than the two other drums?
The reverse gets the least wear, the low band much more, but it's less of a problem with a worn out low band than if the brake band suddenly burns out at the bottom of a long hill so I'm thinking of an experiment - NOS dense cotton lining on the reverse, wood band for the low band and a kevlar band for the brake.. I've got the cotton and wood bands & just don't want to buy a full set of kevlar to use only one band - anybody with one extra narrow kevlar band for sale? (I've mailed Lou Iaccino but maybe I've got the wrong email adress?)
You could braze them up before you throw them in the trash but I don't see the point. The brazing wouldn't make them any less likely to fall apart. Why risk thousands of dollars and lots of labor on a part that costs maybe $150 to replace?
Call there >>> Rocky Mountain Machine Co
3521 E St Vrain, Colorado Springs, CO 80909
(719) 591-7915
I bet he'll sell you anything you want in any quantity you want....... ........AND he does business the old fashioned way: phone, pad, pencil and includes the bill in the box when you receive your order.
He DID say he was experiencing a Kevlar shortage from his supplier but things should be back to normal by now.......
In the spirit of expressing differing opinions. Forty years in the hobby, not nearly as many miles as I wish I had, but more than most.
Mostly, I have used cotton linings. I like them. Even on endurance runs I usually get two years or more between adjustments and have run nearly ten thousand miles on one set.
Wood bands. I am one of the minority. I have had a bad experience with them and not bought any since. The low and reverse were just fine. The brake band would not go more than a hundred miles between adjustments and was useless in way under a thousand miles. That despite the fact that I had excellent outside brakes and hardly even used the transmission brake. I also had two close friends used wood bands once. Their experience was similar extreme wear but on all three bands. Both of these experiences were many years ago (before Guinn).
My theory on this has been for several years that the extreme wear was due to a difference in the grain direction. I used the low a lot and it lasted quite well. Other people have used them with very good success. That is why I rarely comment on my experience with them. But given previous comments, I will this time.
Kevlar. I adjust them loose. I use them like cotton. I can't recall ever adjusting them again, but none of the cars I used them in (like my '16 center-door) stayed with me long enough to need an adjustment.
My boat-tail has a Kevlar in the brake only. Since I got the Bennett Brakes installed, it is adjusted way out and non-functional. I will remove it when I have a little time and put it into another Ts brake.
Some people have used hydramatic linings and other commercial linings in Ts. These are the worst choices because they are also too hard and may contain metal particles which can cause problems with the model T electrical system.
My learned opinions.
Drive carefully, and enjoy, W2
Ken, I agree with Royce. It is not worth the risk to bronze up cracked drums and possibly have them fail, especially as we can now get new drums. I mentioned the ones I found in service purely for interest. They were period repairs which obviously worked, done because there may have been no alternative.
If I was building up a clunker, I have an excellent reverse drum with a crack in the web between the holes. It would be a good candidate for a bronze weld job.
Just for interest.
Allan from down under.
I have three Model T's. One has wood bands, the other two have Kevlar. The first T with the wood bands has had those bands for 20 years and gone on many week long tours up and down hills, and through traffic. I very rarely have to adjust the bands. It does chatter in reverse, and has since the bands were installed.
The second one has Kevlar, and very seldom requires any adjustment. The transmission is smooth in low and reverse. It has been running for 10 years on the Kevlar bands. It has also been on some week long tours including one in Yosemite, which has a lot of hills.
The third car has Kevlar, and I have cracked 2 low drums. My final conclusion was that the low pedal was bent so that the best adjustment for free neutral was with the floor board out and the pedal bottoming out below the level of the floor board. I bent the pedal so that it works with the pedal 1 inch above the floorboard and have a free neutral and can push the car in neutral without turning the engine. It will idle in neutral without moving forward, and I can crank the engine in neutral without the car rolling forward. I put in another drum and new kevlar band. So far have not had another episode with a cracked drum.
All 3 cars have rocky mountain brakes.
I believe that kevlar is only an indirect cause of cracked drums. The primary cause is slipping band which overheats the drum. This slip can be caused either of two ways. 1. too loose band causing slipping when in low gear especially when pulling a steep hill for a long time in low.
2. Too tight band which caused the band to slip on the drum whenever the car is in neutral or high, but not when in low because the pedal is holding the drum tight. Both times the drum cracked I was driving in the same location. I went down a 6% grade in high gear about 45 mph. When I got to the next stop sign, I pushed low and got no response, the pedal went right down to the floor. I adjusted the low and got it to work until the next stop sign and it went to the floor again. That's when I took off the inspection plate and found the lining shreaded.
Three causes of too tight band. 1. Adjusted too tight, the band is tight with the pedal more than one inch above the floor. 2. Worn out cams in the pedal so that the pedal does not move inward when depressed. Therefore the band is adjusted tighter to compensate and causes the drag on the drum. 3. Bent pedal or shaft so that the band has to be over tightened to get the band to depress when the pedal is above the floorboard. In all 3 of these cases, use of wood or cotton bands might not cause the drum to crack, but the life of the band lining would be greatly decreased.
Norm
If a Kevlar band were to somehow, shred or unravel into small threads, how would the individual small threads affect the moving components and bearings of the engine? Being made of such, seemingly, indestructible material, could the individual threads damage the engine? Just wondering. Jim Patrick
Kevlar happened to a second generation member of the Long Beach T Club, and he had to do a full teardown to clean the abrasive fuzz out. Most people probably won't run long enough with a broken drum to have the fuzz do real damage to the bearings. Just guessing.
rdr
Have to pull it out to replace a broken drum anyway, and you can check everything for fuzz while it's off. Most important thing is to clear out the oil line, the holes drilled for oil to the main bearings. Everything else is easily inspected and cleaned by just wiping it out with solvent.
Norm
Chris, It is almost impossible to install the wood lined bands around the drums, without either distorting the bands (oval, instead of round), or cracking the wooden linings.
After repairing or replacing the transmission and are ready to install the wood lined bands, be sure to install the bands while you still have the hogshead off by making each band as round as possible and sliding the bands onto the drums from the rear. This will ensure that the wood lined bands will not be distorted and drag on the drums while the engine is running. Jim Patrick
Thanks for that suggestion, Jim, and to the others for the continuing discussion.
Chris. Here is a good thread from 2010 on securing the wood linings to the bands with rivets. www.mtfca.com/discus/messages/118802/152825.html. Jim Patrick
It took so long to read through this section of threads I almost forgot what it was about. I've never once seen a post here on what a crappy product cast iron is to begin with. Why no vendor has come up with a simple steel drum is beyond me. Cast iron is a very durable material but is porous and susceptible to cracking when over heating. I remember a quote from an engineer for the T-100 project saying something to the effect that this material would never survive todays testing. Iron is junk as it does not dissipate the heat fast enough.
No, actually cast iron is superior to steel for many purposes. Steel has its issues too! In the case of the Model T transmission the cast iron drums are proven to last more than 100 years and for hundreds of thousands of miles if treated properly. I believe the track record is excellent for this part of the car, considering the abuse it has to put up with.
Chris, all that fussing about round bands is only required if you are using Kevlar. The wooden bands will do that for you. You can push a wooden band through the access door if you are careful, but a cracked lining is often the result.
I swear by the pop rivet method. Be absolutely sure you have ALUMINUM pop rivets and then drive out all the pop rivet heads. Next peen the tail ends of the rivets flat against the outside of the bands... that will make installation much easier.
TH
Be sure to wear safety glasses while pop riveting anything. The stems can end up where you least expect them.